Abstract

Two new occurrences of anduoite, (Ru,Os)As2, a rare platinum-group mineral (PGM), are reported from chromitites, one from the Kapitanov deposit, Ukrainian Shield, Ukraine, and the other from the Maja e Sukës deposit, Tropoja ophiolitic massif, Albania. At Kapitanov, anduoite occurs as discrete, homogeneous, euhedral crystals (6–9 and 1–2 μm) enclosed in two chromian spinel grains devoid of fractures. At Maja e Sukës, one crystal of anduoite (3 μm in diameter) belongs to a complex polyphase assemblage of PGM comprising sperrylite, hollingworthite and an unnamed sulfarsenide of Rh, Ir, Pd and Ni. The chemical composition of anduoite is comparable in both deposits: (Ru0.79–0.80Os0.10–0.11Ir0–0.03Rh0.03–0.04Pt0–0.01Pd0.01–0.02Ni0–0.04)∑0.98–1.01(As1.98–2.01S0.01–0.02)∑1.99–2.03. These examples of anduoite have a lower content of Ru than that described from the type locality in Tibet. A magmatic origin is proposed.